1. Field of the Invention
The invention refers to a method for making bags of synthetic material, in which a tubular foil web of synthetic material is advanced respectively in steps corresponding to the length of one bag and cut by means of a transverse cutting knife, and in which a bottom seam is welded by means of a continuously heated pair of welding jaws.
2. Description of Prior Art
A method of this kind is already known from the German laid-open patent 32 04 492. In accordance with this prior art, the tubular web of synthetic material is slightly stretched after being advanced by one bag length and then is severed by lowering a severing knife holder to which the transverse cutting knife is mounted and which is arranged above the tubular foil web of synthetic material. After severing the web, the latter is gripped by the continuously heated pair of welding jaws arranged in direct vicinity to the transverse cutting knife, and the bottom weld seam is formed. However, in conducting this method it is to be observed that the foils of the tubular foil web of synthetic material, lying on top of each other, are slightly crimpled after being severed by means of the transverse cutting knife so that the foils no longer lie flat on top of each other. When the welding jaws are moved into contact with such crimpled tubular foil web of synthetic material, it is often observed that the bottom seam produced by means of the welding jaws is not perfectly made. It can even happen when one layer of foil is no longer gripped by the welding jaws due to a stronger crimpling effect so that at this place, the formed bottom seam is faulty. But even when the welding jaws grip all layers of the tubular foil web of synthetic material, the quality of the formed bottom weld seam is reduced due to the crimpling.